The present invention is directed to a vertical movement capacitive torque sensor for a rotating shaft and more specifically to sensor for automotive applications including steering.
As disclosed in the above copending application, recent requirements from the automotive industry for reduced engine power consumption have dictated the replacement of the power steering hydraulic pump with a much more efficient electric motor geared to the steering shaft to assist the steering effort. The main problem has been sensing the effort being applied by the driver so as to know how much to assist in the steering effort.
The above copending application (of which this is a continuation) discloses a differential capacitive torque sensor where an apertured metal cage shields a dietetic rotor. The relative rotation the apertured cage changes the shielding to thus change the overall differential capacitance of the system to proportionately indicate torque.
It is therefore an object of the present invention to provide an improved vertical movement capacitive torque sensor.
In accordance with the above object, there is provided a vertical movement capacitive torque sensor for a rotating shaft having an axis of rotation and having two portions for which applied torque to one portion causes an angular displacement with respect to the other portion the sensor comprising means for capacitively sensing the angular displacement between shaft portions including, at least one dielectric vane mounted for movement perpendicular to said axis and rotatable with one shaft portion, the vane having a cam surface on which a pin mounted for rotation with the other shaft portion rides and opposes means biasing the vane in a radially outward directions. A pair of concentric capacitor plate rings lying in a common plane encircle one shaft portion and are juxtaposed with the vane. An opposed capacitor plate encircles the other shaft portion and is also juxtaposed with the vane. Electrical bridge means for compare the capacitances formed between the pair of concentric rings and the opposed capacitor plate as modified by the movable vane for determining the angular displacement and applied shaft torque.